Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor | Department of Health Technology and Informatics | en_US |
| dc.contributor.advisor | Chen, Xiangyan (HTI) | en_US |
| dc.creator | Li, Xuelong | - |
| dc.identifier.uri | https://theses.lib.polyu.edu.hk/handle/200/13101 | - |
| dc.language | English | en_US |
| dc.publisher | Hong Kong Polytechnic University | en_US |
| dc.rights | All rights reserved | en_US |
| dc.title | Investigating the underlying metabolic mechanisms and hemodynamic effects of intracranial artery calcification as an imaging biomarker of stroke-serial hospital-based clinical research | en_US |
| dcterms.abstract | Background and purpose | en_US |
| dcterms.abstract | Intracranial arterial calcification (IAC), a highly prevalent finding on head computed tomography (CT) scans, has been reported to be associated with ischemic stroke and cognitive impairment, previously regarded as a proxy indicator of intracranial atherosclerosis. However, the underlying pathophysiologic mechanism linking IAC and cerebral vascular diseases is yet unclear. It is thought that hemodynamics could significantly contribute to the development and progression of atherosclerotic plaques. | en_US |
| dcterms.abstract | Increasing evidence from histopathological findings, coupled with advanced imaging techniques, has shown that IAC can be categorized into two distinct entities: intimal IAC, which often coincides with progressive atherosclerosis, and medial IAC, which is linked to artery stiffness. Furthermore, the difference between intimal and medial calcification in certain specific diseases may indicate the risk factors and processes that drive their development. In this thesis, our goal is to investigate the fundamental metabolic processes indicated by kidney dysfunction and the hemodynamic impacts of IAC, as revealed by pulse wave velocity in cerebral and peripheral arteries detected through ultrasound. Our research findings will provide valuable insights into the underlying mechanism accounting for two distinctive IAC patterns. | en_US |
| dcterms.abstract | Methods and Materials | en_US |
| dcterms.abstract | This series of hospital-based research consists of two main cohorts. Each cohort included consecutive patients who were admitted to the Department of Neurology and underwent thin-slice brain CT scans during their hospitalization. The extent of IAC, measured by IAC scores, was evaluated on non-contrast head CT images. The IAC was then classified as either intimal or medial calcification. Arterial stiffness was using Brachial-ankle pulse wave velocity (baPWV) and carotid–cerebral pulse wave velocity (ccPWV). The function of kidney was assessed using the estimated glomerular filtration rate (eGFR), which was calculated based on a modified equation for estimating the glomerular filtration rate. | en_US |
| dcterms.abstract | Results | en_US |
| dcterms.abstract | In the first hospital-based cohort including a total of 516 patients (mean+/-SD) exploring the underlying metabolic mechanisms of two distinct IAC patterns, IAC was identified on brain CT in 440 patients (85.27%). Among these, 189 (42.95%) patients had predominant intimal calcifications, while 251 (57.05%) had predominant medial calcifications. Multivariate analysis revealed that lower eGFR level (eGFR <60 ml/min/1.73 m2) was associated with higher IAC scores (OR 2.01; 95% CI, 1.50–2.71; p < 0.001). Medial calcification was more frequent in the group with a lower eGFR (eGFR <60 ml/ min/1.73 m2) compared to the other two groups with eGFR 60 to 89 and eGFR>90 ml/min/1.73 m2 (78.72% vs. 53.65%, p <0.001; 78.72% vs. 47.78%, p < 0.001). In a multivariable analysis, impaired kidney function was associated with an increased likelihood of medial calcification presence in patients with eGFR <60 ml/min/1.73 m2 (OR, 1.47; 95% CI, 1.05 to 2.06). | en_US |
| dcterms.abstract | Simultaneously, the relationship between IAC and serum phosphorus concentration (SPC) was analyzed based on the same cohort. Data analysis showed that higher serum phosphorus was a significant risk factor for moderate/severe IAC in patients with eGFR ≥60 ml/min/1.73 m2 (OR, 1.27; 95% CI, 1.01-1.59; P <0.05) and eGFR <60 ml/min/1.73 m2 (OR, 1.92; 95% CI, 1.04-3.57; P <0.05), using those with mild IAC as the reference group. However, a higher SPC was linked to an increased likelihood of medial calcification only in patients with eGFR <60 ml/min/1.73 m2 (OR, 1.67; 95% CI, 1.08 to 2.61). | en_US |
| dcterms.abstract | In the second hospital-based cohort including 143 stroke patients (18 to 80 years old), investigating the relationship between IAC and baPWV, a higher prevalence of IAC was noted across increasing baPWV quartiles (Q1: 53 %, Q2: 69 %, Q3: 86 %, Q4: 94 %, P < 0.001). IAC scores were also accelerated with increasing ccPWV values (1.60 ± 1.71; 2.56 ± 1.99; 3.44 ± 1.91; 4.64 ± 1.58. P < 0.001). After adjusting age and hypertension, the odds ratio (95 % confidence interval) for the IAC scores was 1.61 (1.06–2.45; P = 0.025) in the top quartile of baPWV compared with those in the lowest quartile. | en_US |
| dcterms.abstract | Meanwhile, the same cohort was used to examine the relationship between IAC and ccPWV. The prevalence of IAC also increased in line with the ccPWV quartile, with rates of 54%, 76%, 83%, and 89% for quartiles 1, 2, 3, and 4, respectively (p<0.001). IAC scores followed a similar pattern, with median [interquartile range] values of 0 [0–2], 3 [2–4], 4 [2–5], and 5 [4–6], respectively (p<0.001). After further adjusting for age and hypertension, a significant correlation was only observed between quartiles 3 and 4 of ccPWV and IAC scores. The odds ratio (95% confidence interval) for the IAC scores was 1.78 (1.28–2.50) (p=0.001) in quartile 4 of ccPWV and 1.45 (1.07–1.95) (p=0.015) in quartile 3 when compared with quartile 1. | en_US |
| dcterms.abstract | Conclusions | en_US |
| dcterms.abstract | Our research findings, based on two cohorts of hospitalized patients, addressed two clinical questions related to IAC. The findings from the first cohort indicated that impaired renal function was independently associated with a higher degree of calcification in intracranial arteries, particularly medial calcification. This highlights a distinction between two types of intracranial arterial calcification and suggests the potential for targeted prevention of lesion formation and cerebrovascular diseases. Our second cohort-based study found that the degree of cerebral arterial calcification was correlated with peripheral arterial stiffness, as evaluated by baPWV, and cerebral arterial stiffness, as measured by ccPWV, in patients with acute ischemic stroke. This suggests that IAC significantly changes the hemodynamic parameters within cerebral arteries and could be a contributing factor to the onset of cerebral artery diseases. | en_US |
| dcterms.abstract | Longitudinal studies will be performed to further validate the clinical significance of IAC in predicting cerebrovascular disease in the general population, and in predicting clinical outcome of stroke patients. | en_US |
| dcterms.extent | 135 pages : color illustrations | en_US |
| dcterms.isPartOf | PolyU Electronic Theses | en_US |
| dcterms.issued | 2024 | en_US |
| dcterms.educationalLevel | Ph.D. | en_US |
| dcterms.educationalLevel | All Doctorate | en_US |
| dcterms.accessRights | open access | en_US |
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